If dealing with nested parent-child-structures, it happens that
the proper UID of a record (either parent or child) has not been
persisted yet and therefore it's only a "NEW..." which will be
replaced in a later step during several "remapping" actions.

If copying a page with many sub-pages and sub-records this
remap action is processed very late. Results are invalid record
relations (like content elements now having duplicated images
since the remapping has not updated the real parent pointer yet).

This patch is marked with [!!!] since side-effects can appear.
In case this change gets merged and it turns out that DataHandling
got worse, it's target to be reverted again.